WASHINGTON — Justice David Souter never danced the salsa in public. Justice John Paul Stevens doesn't sing in karaoke bars. And Chief Justice John Roberts hasn't thrown out the first pitch at Yankee Stadium.

But that was yesterday's Supreme Court. The newest justice, Sonia Sotomayor, has done all three of those things — in the less than two months since she replaced Souter on the court.

While the Supreme Court is all about the law, personalities matter. As the court begins its new term Monday, the justices will be dealing not only with the cases in front of them but with a wild card: how Sotomayor and her effervescence may change things.

"It's like when you were little and a new kid joined the class," said Stephen Wermiel, a constitutional law professor at American University. "There was always a little air of excitement or anticipation because you didn't know how it would change the dynamic."

The earliest indications are that she is unlikely to affect the outcome or alter the terms of debate in two of the high-profile cases that probably will dominate the term: a challenge to limits on corporate spending in political campaigns and a lawsuit seeking to strike down local handgun bans in the Chicago area.

In both cases, conservative majorities that prevailed in earlier cases appear solid. Sotomayor probably will side with the court's liberals in dissent from decisions in favor of gun rights and loosening campaign finance restrictions, as the now-retired Souter did.

But other disputes loom and, to cite just one area, Sotomayor will be watched closely to see whether her past as a prosecutor makes her more sympathetic to law enforcement in criminal cases. Unlike her colleagues, Sotomayor also has experience as a trial judge.

On the docketThe criminal docket includes challenges to handing out life sentences with no chance of parole to people younger than age 18. These cases follow the court's recent decision to bar the execution of people who committed murder as juveniles.

The court has scheduled arguments in First Amendment cases over the separation of church and state involving a cross in the Mojave National Preserve in California that serves as a World War I memorial, and free speech issues in the government's efforts to criminalize the production of videos of dog fights and other acts of animal cruelty.

The justices themselves say any change in the court matters.

"It's a new court. When I was trying jury cases, which is usually 12, if a juror had to be replaced because one was ill or something ... it's just a different dynamic. It was a different jury. And it's the same way here. This will be a very different court," Justice Anthony Kennedy said in an interview for C-SPAN's new documentary on the court.

Sotomayor is the third new justice on the court since 2005, when Roberts was confirmed as the first of President George W. Bush's two nominees. Justice Samuel Alito came on board early in 2006.

For the moment, Roberts and the other conservatives — Alito and Justices Antonin Scalia and Clarence Thomas — continue to appear ascendant, joined by Kennedy, a swing voter who sides more often than not with the conservatives in cases with a clear ideological division.

Their biggest show of strength could come in the campaign finance case. It could result in the reversal of decades-old restrictions on corporate and union spending in elections and demonstrate the political importance of Bush's appointments.

"It's an enormous test for Chief Justice Roberts and the conservatives on the court. Dramatic changes in the law are being urged upon them," said Doug Kendall, leader of the liberal-leaning Constitutional Accountability Center public interest group that closely follows the court.

Look aheadIndications are that more change in the makeup of the court could come soon. Justice John Paul Stevens, who turns 90 in April, acknowledged last month that he has so far hired fewer law clerks than usual for next year, a move widely considered to be a signal that he is at least contemplating retiring.

Justice Ruth Bader Ginsburg, 76, appears well after her surgery for pancreatic cancer in February and has said she plans to serve into her early 80s. But the long-term prognosis for pancreatic cancer is poor.

The retirement of either justice would give President Barack Obama, who named Sotomayor, another nominee, although the ideological balance of the court probably would not change. For that to happen, one of the conservatives would have to leave during Obama's presidency. None of the current conservative justice has even hinted at retirement.

Deanne Maynard, a Supreme Court advocate at the Morrison and Foerster law firm and herself a former high court law clerk, said any short list of prospective nominees would include women, even if Stevens and not Ginsburg retires first.

"It's very intriguing, to me at least, that there'd be three women on the court," Maynard said.

Video: Big choices loom

Closed captioning of: Big choices loom

>>>the
supreme court
goes into session. the court has plenty of work waiting, including questions regarding
freedom of speech
and religion. our justice correspondent
pete williams
has a preview.

>>reporter: the court will decide what's to become of a seven foot tall cross in
southern california
's
mojave desert
, now a
national preserve
. crosses have stood there since
1934
as a
war memorial
, but the current one is covered with plywood, caught up in a court fight over whether it's an unconstitutional religious symbol on
federal land
. the former employee of the desert preserve is suing. his lawyer says it's improper government favoritism toward one religion.

>>a number of high ranking
military officers
have come in and said, this is not a message the military should be sending that we honor our christian veterans but we don't honor our other veterans.

>>reporter: but the vfw and other veterans groups are fighting to keep it.

>>to most americans, the idea of tearing down a war monument that's been up for 75 years is something that is highly distasteful, and that is inappropriate.

>>reporter: the court will referee a
freedom of expression
battle brought by a virginia man over a
federal law
that makes it a crime to sell videos of dogfights and other dictions of
animal cruelty
. the government says such material is like
child pornography
, encouraging illegal behavior and deserving no
free speech
protection.

>>hi, i'm
bob stevens
.

>>reporter: but a lawyer for
robert stevens
, who sells the videos, says banning them goes too far.

>>under our first amendment, we let the people themselves decide what the value of speech is. we don't have the government decide it for us.

>>reporter: in a case that could change the landscape of
political campaign
, makers of a documentary attacking
hillary clinton
's run for president urge the court to strike down laws that restrict corporations and aunions from using their own money to buy
campaign ads
. the justices will also decide whether the second amendment's right to own a gun should apply nationwide that would apply a new round of challenges to
gun control
laws. and the government will decide whether it's constitutional for the
federal government
to continue holding people deemed dangerous
sex offenders
, after they've served their sentences. and all eyes will be on
justice john paul stevens
. he has hired fewer
law clerks
than usual for next year's term, prompting speculation he might step down next summer.
pete williams
, nbc news, at the
supreme court
.